Massage device



Oct. 30, 1 956 I WAHL 2,768,621

MASSAGE DEVICE Filed April 1, 1953 460 Jaw;

United States Patent MASSAGE DEVICE Leo J. Wahl, Sterling, 111., assignor to Wahl Clipper Corporafion, Sterling, 111., a corporation of Illinois Application April 1, 1953, Serial No. 346,108 2 Claims. (Cl. 128-41) My invention relates to a massage device of the type adapted to be mounted on the back of an operators hand. Such a device transmits vibrations to the operators fingers which in turn are applied to desired parts of the body for massage purposes.

My U. S. Patent No. 1,832,437 illustrates one of my prior massage devices, while my earlier U. S. Patent No. 1,818,287 (issued on a later filed application) shows the device equipped with a hand mounting attachment. My present invention relates to the same general type of device.

The massage device of this invention and those of my prior patents is of the type which uses an electromagnet and an armature to produce the desired vibrations. It comprises an electromagnet of substantial mass and an armature mounted in eifective relation with the electromagnet. The latter is energized by alternating or pulsating current and the armature is successively attracted and released by the electromagnet to produce vibrations suitable for massage. The armature is the element which is associated with the operators hand.

Electromagnetic massage devices of this character necessarily are tuned to vibrate at a resonant frequency which is a multiple of the frequency of the alternating or pulsating current applied to the electromagnet. Usually the tuned frequency of the device is related to the frequency of the applied current by a factor of one, although factors of two or more are possible.

As is well known, a vibrating device of this character is tuned by assigning proper mass to both the electromagnet and the armature, and by providing a matiching resilient connection between the two. Proper selection of these variables, of course, requires consideration of the value of the voltage applied to the electromagnet as well as its frequency.

Prior massage devices of this character have been tuned to vibrate at resonant frequency under conditions when the device is not mounted on the hand of an operator. This means that the vibrational energy delivered by the device is substantially at maximum when the device is unmounted. In other words, when the device is held loosely in the hand and the current turned on, the device vibrates with maximum energy in a manner which is regarded as somewhat objectionable. This is a practical shortcoming of the electromagnetic type device.

Competing massage devices utilize a rotary motor with an eccentric to produce vibratory action. This type of massage device is substantially free of the aforesaid objection present in the electromagnetic type. Despite the fact that the rotary motor type is considerably more expensive to manufacture than the electromagnetic type, the former is preferred by many because of its freedom from objectionable vibration when held loosely in the hand.

One object of my invention, therefore, is to provide an electromagnetic type massage device which is substantially free of objectionable vibration when unmounted.

Another object of the invention is to provide an im- 2 proved electromagnetic type massage device which can be constructed at a cost which does not exceed that of present electromagnetic type devices. This cost, as previously mentioned, is substantially below that of competing motor driven devices.

My invention contemplates the provision of an electromagnetic type massage device which is substantially the same with those shown in my aforesaid prior patents with the exception that my present device is tuned in accordance with a new principle. Rather than tuning the device for resonant operation when unmounted, in accordance with this invention 1 tune the device for resonant operation when it is mounted on the operator's hand. In other words, I take into consideration the mass of the operators hand indesigning the device for resonant operation. As a result, the device is substantially detuned and non-vibratory when unmounted. This, of course, eliminates the aforesaid objection to prior electromagnetic type massage devices.

Other objects, advantages and details of my invention will appear as the description proceeds, reference being had to the accompanying drawing wherein one form of the invention is shown. It is to be understood that the description and drawing are illustrative only, and that the scope of the invention is measured by the appended claims.

In the drawing, the single figure is a view in side elevation, partly broken away, of a massage device embodying my invention.

In one common form, an electromagnetic type massage device includes an E-shaped core 5, an energizing coil 6 on the core, an armature 7 in effective relation to the face of the core, a resiliently biased hinge 8 interconnecting the armature and the core, directly or indirectly, and means 9 for mounting the armature on the back of an operators hand. The core and coil (the electromagnet) have substantial mass and may be regarded as the inertia portion of the device against which the armature or moving portion reacts.

In a more complete form, the device includes a casing 10 which is mounted on the armature and encloses the core, coil, armature and biased hinge arrangement.

The hinge arrangement 8, in the usual form of the device, comprises a leaf spring of predetermined stiffness which intermediate its ends is curved to provide a right angle bend, one end of the spring being attached to core 5 and the other to armature 7.

In the practice of the present invention, the biased hinge or leaf spring arrangement 8 which interconnects the armature and the core, directly or indirectly, has a stiffness which exceeds by about 8%l2% the stiffness required to produce resonant vibration when the device is unmounted. This extra stiffness provides a stifliciently detuned condition so that the device is substantially non-vibratory when not applied to the hand. It is true that low amplitude, forced Vibrations do occur, but the energy developed thereby is so low that it is wholly unobjectionable.

When a device tuned as aforesaid is applied to an operators hand, the mass of the hand added to that of the armature establishes a new relationship between the parameters of the system. The new relationship is such that the device is then tuned to vibrate at resonance. Thus, the vibratory energy output of the device when mounted is at maximum, and the device operates at desired efiiciency.

A device constructed in accordance with my invention, in addition to eliminating the objectionable vibrations which occur when the device is unmounted, in fact operates with improved efliciency when it is mounted on the hand. This is because prior devices experienced a certain amount of detuning and corresponding loss of efliciency when mounted for operation.

From the above description it is thought that the construction and advantages of my invention will be readily apparent to those skilled in the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A massage device for attachment to the back of an operators hand comprising an E-shaped core, an energizing coil on said core, an armature in etfective relation to the face of said core, a leaf spring interconnecting said armature and said core and means mounting said armature to the back of an operators hand, the said leaf spring exceeding by about 8%-l2% the stiffness of a spring required to produce resonant vibration when the device is not applied to the hand whereby the device produces resonant vibrations when applied to the hand and is substantially non-vibratory when not applied to the hand.

2. A massage device for attachment to the back of an operators hand comprising a core, an energizing coil on said core, an armature in effective relation to the face of said core, a biased hinge interconnecting said armature and said core and means mounting said armature to the back of an operators hand, the stiffness of the bias of said hinge exceeding by about 8%12% the stiffness of a bias required to produce resonant vibration when the device is not applied to the hand whereby the device produces resonant vibrations when applied to the hand and is substantially non-vibratory when not applied to the hand.

References Cited in the file of this patent UNITED STATES PATENTS 

